When the Yankees decided not to bring back Joe Girardi as a high-priced backup catcher, many thought his departure would severely diminish the two-time defending champions’ chances of earning another World Series banner.

Not Girardi.

“I loved being with the Yankees and all the stuff that happened there,” Girardi said yesterday at Shea, where the Mets swept a doubleheader from the Cubs, 8-3 and 7-6. “But I didn’t fit there anymore. It was Jorge [Posada]’s time. I knew it and they knew it.”

Some didn’t. When Girardi arrived via free agency from the Rockies after the 1995 season, the veteran didn’t provide a great deal of offense, but his ability to handle the Yankees’ pitching staff made him an integral part of the team’s success. Several Yankee pitchers made known their preference for Girardi and Posada’s 17 passed balls in 1999 did nothing to instill confidence.

“That was a tough situation,” Girardi said. “It makes sense that they were more comfortable with me because I had been around longer, but the only way that was going to change is if Jorge was given the job. He deserved that opportunity.”

And Posada has made the most of it, hitting over .300 and performing ably behind the plate so far this year. Girardi, meanwhile, packed up and went back to the Cubs, the team that originally drafted him in the fifth round in 1986.

“That made it easier,” Girardi said. “I was familiar with the surroundings [in Chicago] and it was obvious they wanted me. It’s a real good situation.”

That may be so, but Girardi isn’t likely to extend his post-season streak, which reached five seasons last year. Girardi made the playoffs in his final season with Colorado and the past four in The Bronx. The Cubs, under first-year manager Don Baylor, will likely need more than Girardi’s wisdom and experience to get them through the NL Central, where the Cardinals, Astros and Reds are all fairly strong.

“Joe is going to give us exactly what we need,” Baylor said. “He isn’t the biggest offensive threat, but he’s invaluable when it comes to working with the young talent we have. With that, he hasn’t disappointed and he won’t.”

Still, while not nearly as much was expected of Girardi at the plate as behind it, he needs to produce more than he has. He is hitting a sickly .186 after going 1-for-4 in the doubleheader. Worse, his single in the ninth inning of the first game gave him his first RBI of the season.